Field of the Invention
The present invention relates to a shift control method and apparatus for a vehicle.
Description of the Related Art
Vehicle companies develop ISG (Idle Stop and Go) vehicles integrated with eco-friendly, high fuel efficiency, idling prevention technologies according to worldwide high oil prices and reinforced environment regulations. Although these technologies are currently applied only to compact vehicles, the application thereof is gradually expanded so that all vehicles have them as basic functions.
In an ISG vehicle, an engine enters an idling state when an ISG mode is operated (when the engine is turned off), the engine is automatically stopped when a predetermined condition is satisfied, and the engine is automatically restarted when a brake pedal is released, or the tip-in of an accelerator pedal or a starting intention according to a change in gear position is detected. In this case, in order to restart the engine of the ISG vehicle, a constant hydraulic pressure is supplied to the solenoid of a transmission by means of an electrical oil pump.
Meanwhile, some of ISG vehicles use mechanical oil pumps in place of electrical oil pumps in order to achieve a reduction in cost, a reduction in weight, and an improvement in fuel efficiency. However, in the ISG vehicle using the mechanical oil pump, since a hydraulic pressure completely falls in a solenoid when an engine is turned off during an ISG mode, it takes a long time to supply the hydraulic pressure to the solenoid by means of the mechanical oil pump when the engine is restarted after it is turned off. For this reason, there is a problem in that a variation in shift time is generated when the engine is restarted.